A conventional AWD driveline for a motor vehicle may include a primary front drive axle coupled to a secondary or auxiliary rear drive axle. When the driveline is operating in a 4×2 mode of operation (i.e., four wheels, with two of them operating as driving wheels), the primary front drive axle must provide tractive forces not only to keep the motor vehicle moving, but also to overcome the frictional losses of the secondary or auxiliary rear drive axle that is being driven through the tire/road surface interface. Driveline losses may be due to oil churning losses, viscous drag, inertia, as well as friction.
In an effort to minimize loss and provide a more fuel efficient driveline when in a 4×2 mode of operation, it may be desirable to have the ability to completely idle the secondary or auxiliary drive system, including the secondary or auxiliary rear drive axle.